The forks on x-mart bikes are usually threaded. You cannot upgrade these forks to a better, threadless fork.
If you are looking to upgrade a bike, you'll need an upgradable bike first. Head out to your local bike shop and get a decent bike. You'll enjoy this one much better the first time you get on it- the frame will actually be sized correctly for your body. You can even test ride a few different bikes to find out which geometry you like best.